In the related art, a dehumidifying system has been proposed in which a rotating desiccant rotor supported by an adsorbent that carries out adsorption and desorption of moisture is used, and in which a heat exchanger of a heat pump is used as a regenerative heat source of a desorption portion of this desiccant rotor. This dehumidifying system is configured to carry out a continuous dehumidifying operation by disposing a desiccant rotor in an air passage through which air of a dehumidification target space circulates and by making the desiccant rotor rotate, and, further, by passing air through heating means serving as a regenerative heat source, the desorption portion of the desiccant rotor, cooling means, and an absorption portion of the desiccant rotor in this order (see Patent Literature 1, for example).